Bonaca, Ana and Conroy, Charlie and Hogg, David W. and Cargile, Phillip A. and Caldwell, Nelson and Naidu, Rohan P. and Price-Whelan, Adrian M. and Speagle, Joshua S. and Johnson, Benjamin D. (2020) High-resolution Spectroscopy of the GD-1 Stellar Stream Localizes the Perturber near the Orbital Plane of Sagittarius. The Astrophysical Journal, 892 (2). L37. ISSN 2041-8213
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Abstract
The 100° long thin stellar stream in the Milky Way halo, GD-1, has an ensemble of features that may be due to dynamical interactions. Using high-resolution MMT/Hectochelle spectroscopy we show that a spur of GD-1-like stars outside of the main stream are kinematically and chemically consistent with the main stream. In the spur, as in the main stream, GD-1 has a low intrinsic radial velocity dispersion, ${\sigma }_{{V}_{r}}\lesssim 1$ $\mathrm{km}\,{{\rm{s}}}^{-1}$, is metal-poor, [Fe/H] ≈ −2.3, and has little intrinsic spread in the [Fe/H] and [α/Fe] abundances, which point to a common globular cluster progenitor. At a fixed location along the stream, the median radial velocity offset between the spur and the main stream is smaller than 0.5 $\mathrm{km}\,{{\rm{s}}}^{-1}$, comparable to the measurement uncertainty. A flyby of a massive, compact object can change orbits of stars in a stellar stream and produce features like the spur observed in GD-1. In this scenario, the radial velocity of the GD-1 spur relative to the stream constrains the orbit of the perturber and its current on-sky position to ≈5000 deg2. The family of acceptable perturber orbits overlaps the stellar and dark-matter debris of the Sagittarius dwarf galaxy in present-day position and velocity. This suggests that GD-1 may have been perturbed by a globular cluster or an extremely compact dark-matter subhalo formerly associated with Sagittarius.
Item Type: | Article |
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Subjects: | AP Academic Press > Physics and Astronomy |
Depositing User: | Unnamed user with email support@apacademicpress.com |
Date Deposited: | 27 May 2023 05:07 |
Last Modified: | 06 Jul 2024 06:51 |
URI: | http://info.openarchivespress.com/id/eprint/1371 |